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-rw-r--r--lib/mpi/mpicoder.c55
1 files changed, 26 insertions, 29 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 823cf5f..7150e5c 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -237,16 +237,13 @@ EXPORT_SYMBOL_GPL(mpi_get_buffer);
* @a: a multi precision integer
* @sgl: scatterlist to write to. Needs to be at least
* mpi_get_size(a) long.
- * @nbytes: in/out param - it has the be set to the maximum number of
- * bytes that can be written to sgl. This has to be at least
- * the size of the integer a. On return it receives the actual
- * length of the data written on success or the data that would
- * be written if buffer was too small.
+ * @nbytes: the number of bytes to write. Leading bytes will be
+ * filled with zero.
* @sign: if not NULL, it will be set to the sign of a.
*
* Return: 0 on success or error code in case of error
*/
-int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
+int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned nbytes,
int *sign)
{
u8 *p, *p2;
@@ -258,43 +255,44 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
#error please implement for this limb size.
#endif
unsigned int n = mpi_get_size(a);
- int i, x, y = 0, lzeros, buf_len;
-
- if (!nbytes)
- return -EINVAL;
+ int i, x, buf_len;
if (sign)
*sign = a->sign;
- lzeros = count_lzeros(a);
-
- if (*nbytes < n - lzeros) {
- *nbytes = n - lzeros;
+ if (nbytes < n)
return -EOVERFLOW;
- }
- *nbytes = n - lzeros;
buf_len = sgl->length;
p2 = sg_virt(sgl);
- for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB,
- lzeros %= BYTES_PER_MPI_LIMB;
- i >= 0; i--) {
+ while (nbytes > n) {
+ if (!buf_len) {
+ sgl = sg_next(sgl);
+ if (!sgl)
+ return -EINVAL;
+ buf_len = sgl->length;
+ p2 = sg_virt(sgl);
+ }
+
+ i = min_t(unsigned, nbytes - n, buf_len);
+ memset(p2, 0, i);
+ p2 += i;
+ buf_len -= i;
+ nbytes -= i;
+ }
+
+ for (i = a->nlimbs - 1; i >= 0; i--) {
#if BYTES_PER_MPI_LIMB == 4
- alimb = cpu_to_be32(a->d[i]);
+ alimb = a->d[i] ? cpu_to_be32(a->d[i]) : 0;
#elif BYTES_PER_MPI_LIMB == 8
- alimb = cpu_to_be64(a->d[i]);
+ alimb = a->d[i] ? cpu_to_be64(a->d[i]) : 0;
#else
#error please implement for this limb size.
#endif
- if (lzeros) {
- y = lzeros;
- lzeros = 0;
- }
-
- p = (u8 *)&alimb + y;
+ p = (u8 *)&alimb;
- for (x = 0; x < sizeof(alimb) - y; x++) {
+ for (x = 0; x < sizeof(alimb); x++) {
if (!buf_len) {
sgl = sg_next(sgl);
if (!sgl)
@@ -305,7 +303,6 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
*p2++ = *p++;
buf_len--;
}
- y = 0;
}
return 0;
}
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